This invention pertains to electrical lampholders of the socket type, and more particularly, is concerned with lampholders having over temperature protection.
Under a variety of circumstances, lamp heat can build up to excessive levels and damage nearby wiring and fixtures. In response to this danger, thermal protectors for incandescent lamps have been located in the electrical circuit upstream from the lamp. Unfortunately, in most installations, the protector is some distance away from the lamp, and does not react in direct response to lamp heat but to current and ambient temperature. This arrangement may respond to an overrated lamp being used, but would not respond rapidly, if at all, to heat build up due to mechanical causes such as poor air circulation.
U.S. Pat. No. 4,131,868, describes a lampholder containing a thermal protector to shut off current flow to the lamp when the lampholder is heated above a predetermined temperature. The thermal protector called for is not a packaged device but is assembled from separate pieces during manufacture of the lampholder.
This arrangement was an advance of the state of the art but can be improved upon. The protector has to be calibrated after manufacture of the lamp assembly which can be an awkward procedure. The protector's contacts are exposed and may spark when the protector is tripped. It would be advantageous to utilize a precalibrated shock resistant hermetically sealed protector which may be gas filled to ensure both maximum thermal transfer and arc suppression for greater contact life.